1. To the bolded: Al improved as an all-around player under Corbin. He was terrible in the (roughly) 50 games he played under Sloan (with Deron).
2. Neither Paul nor Al played noticeably better last season than they did under Corbin.
I disagree. First, are you saying that Corbin is a better coach than Clifford and Budenholzer? I don't think you are, but your comments lead to that conclusion. Clifford coached a 28 win Hornets team to a 43-39 record, turned them into one of the best defensive teams in the NBA, with Al Jefferson as the main scorer. You could try to argue that Corbin is better than Bud. His WL record is similar to Corbins. But if you watched the Hawks play last season you know he's a better coach.
That being said, you're wrong about both players performances last season. They were noticeably and statistically one of their best seasons. Al had one of the best statistical seasons he's ever had, averaging 21 and 10. If you watched him last season, I never saw him play like that in Utah. Plus he played on one of the best defensive teams in the NBA, something the Jazz never even sniffed. We all know Al's defensive rep here and around the league. As for his Sloan 1/2 year. How can you count that considering the circumstances? I'll give you his improved passing, but thats it. You have to credit his new coach for this improvement, and give some credence to Corbin's inept coaching to his lack luster performance, especially defensively, here.
Paul was an All Star, granted in the East. But he put up 17.9 (18) pts, 8.5 rebs, and 3 asst. All career highs, outside of rebs (his high is 8.6). He was better last season than any other with the Jazz. Period. Paul is a good player, but you have to give credit where it's due. He was put in a position to succeed, and his coach can take a lot of credit there.
Coaching matters, especially when players are young. I would say Corbin's short comings hurt out young players even more than the vets, who obviously struggled more under Corbin. His scheme was obviously flawed and he wasn't able to execute his plan. He had questionable relationships with the players, notably Hayward. He was a bad coach, and bad coaches fail.
If I'm wrong, lets hear it with more than conjecture.